The renewal loop re-posted the challenge every time it polled and found the
authorization still pending. RFC 8555 section 7.5.1 has the client post a
challenge once to say it is ready and then poll; a server that has already
moved the challenge to "processing" refuses a second post, and pebble
answers 400 malformed, which failed the whole renewal.
Verified against pebble: the 400s are gone and the client polls. The suite
still can't finish on this machine, because pebble never reaches the test
server to validate the challenge; that path is the environment, and the
runbook now says so.
jcoffey-dev
309835be1d